Prison chiefs are to pay £120,000 to seven former young offenders who complained they were assaulted by officers, it emerged today.

The seven claimed they were punched, slapped, kicked and had their heads slammed repeatedly against the floor by segregation block wardens at Portland young offenders' institution (YOI) in Dorset.

The Prison Service's out of court settlement came just days before a lengthy legal case was due to begin at Weymouth County Court.

The Howard League for Penal Reform, whose investigation prompted the case, renewed its calls for a public inquiry into the affair, which has led to two officers being dismissed but no criminal convictions.

The male prisoners were aged between 16 and 21 at the time of the assaults and complained that officers also tore clothes off them during strip searches.

Some were put on false charges of assaulting officers and punished by having extra days added to their sentences, said solicitor Nogah Ofer.

"These seven are only the tip of an iceberg," she said. "The police investigated 53 cases dating back to the 1980s.

"A culture of intimidation and brutality has been deeply entrenched in Portland for decades."

The YOI was criticised in 1999 by the then Chief Inspector of Prisons, Sir David Ramsbotham, for its overly "militaristic" regime.

Although police sent files regarding 31 allegations to the CPS, dating back five years. the Crown Prosecution Service decided to bring no charges against any officer in 2001.

An internal investigation found assaults had taken place and two officers were dismissed, it emerged in June 2002.